1. Field of the Invention
This invention relates a cellulosic polymer, a blood-treating device and a process for producing the same. More particularly, the present invention aims at providing a blood-treating device which makes it easy to remove phosphoric acid ions and to further improve bio-compatibility.
2. Description of the Related Art
A dialysis membrane for the purification of blood comprising regenerated cellulose has long been known, and has primarily been used at present, too, as a material for an artificial kidney. Accordingly, a large number of attempts have been made to date to modify the regenerated cellulose.
Japanese Examined Patent Publication (Kokoku) No. 57-35018 discloses a hemodialysis membrane obtained by chemically bonding an antithrombogen compound to a cellulose, and German Patent No. 1720087 discloses a membrane with anti-coagulation of blood obtained by first reacting a membrane material with a halogenated alkyl and then with an alkali salt of an antithrombogen compound having a cationic group. Further, Japanese Unexamined Patent Publication (Kokai) No. 61-8105 discloses a dialyzer mainly having a feature thereof in that a reaction product between a hydroxy compound and a polyfunctional isocyanate is chemically bonded to the regenerated cellulose. Japanese Unexamined Patent Publication (Kokai) No. 61-113459 discloses a dialyzer using a diethylaminoethylcellulose and a sulfoethylcellulose at a specific proportion.
All of the prior art references described above disclose the membranes having improved biocompatibility, particularly anti-coagulation of blood, prevention of leukopenia and anti-complement activity.
On the other hand, removal of phosphorus is not sufficient during dialysis of patients affected by chronic renal insufficiency. Phosphorus cannot be removed by ordinary dialysis because phosphoric acid ions have charge or form a complex with proteins and thereby exhibits a behavior similar to a solute having a large molecular weight. Residual phosphorus is believed to result in acidosis.
Accordingly, an alumina gel has been used favorably to correct this acidosis, but since it has been clarified that a trace amount of Al.sup.3+ absorbed is associated with encephalopathy, an excessive use of the alumina gel has become a problem. For this reason, the development of a membrane capable of easily removing the phosphoric acid ions by dialysis has been earnestly desired.